> >> <>I'm not sure I made myself clear enough. A gun barrel does not 
> >> fulfill my criteria; it is too thin and probably would 
> heat up fairly 
> >> uniformly. It probably expands (inside and out). They 
> probably have 
> >> found a way to deal with that
> >
> They did. since the beginning of fire arms.  They stooped 
> shooting until the barrel cooled down.
> 
> But you cannot compare the hole in the middle of a hollow 
> cylinder to a flat sheet.  A cylinder or pipe or tube is just 
> a flat sheet formed in an endless circle, so to speak.
> 
> Think about when they made wood wagon with the steel rims or 
> wooden barrels.  They evenly heated steel rings and dropped 
> them over the wheel or barrel when the ring cooled it shrunk 
> and  held the barrel or wheel together.


No, the hot barrel causes the shell to fire (or detonate) prematurely (bad
for staff morale), and increases wear.  I don't spend any time firing guns
so I could be wrong.

The wagon wheel example merely proves the case.  I can make the steel rim by
bending a strip of metal into a circle, or I can drill a very big hole in a
metal plate.  What's the difference?  Metal is metal.  Both methods give me
a metal ring.  There's no magic point when the thickness causes the hole to
shrink, unless it's big enough for gravity to play a part.

Consider a square hole.  I can file out the cylinder to get the square hole.
Would it shrink when heated?  Will a flat plate expand when heated?  If I
weld four of them together to match the cylinder, then what?

Tony

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